Monday, June 24, 2013

New paper finds no change of snow cover in the Alps over past 27 years & 'deceleration of the snow trend'

A forthcoming paper in The Cryosphere finds no change in snow cover of the European Alps over the past 27 years from 1985-2011. The authors instead find the snow trend in the Alps may be decelerating, stating, "our results do not show any significant trends in the monthly mean SCA [snow cover anomaly] over the last 27 years. This is in agreement with other research findings and may indicate a deceleration of the decreasing snow trend in the Alpine region."

The red dashed line indicates a linear trend in Alpine snow cover of zero.

Abstract: Seasonal snow cover is of great environmental and socio-economic importance for the European Alps. Therefore a high priority has been assigned to quantifying its temporal and spatial variability. Complementary to land-based monitoring networks, optical satellite observations can be used to derive spatially comprehensive information on snow cover extent. For understanding long-term changes in alpine snow cover extent, the data acquired by the Advanced Very High Resolution Radiometer (AVHRR) sensors mounted onboard the National Oceanic and Atmospheric Association (NOAA) and Meteorological Operational satellite (MetOp) platforms offer a~unique source of information.

In this paper, we present the first space-borne 1 km snow extent climatology for the Alpine region derived from AVHRR data over the period 1985–2011. The objective of this study is twofold: first, to generate a new set of cloud-free satellite snow products using a specific cloud gap-filling technique and second, to examine the spatiotemporal distribution of snow cover in the European Alps over the last 27 yr from the satellite perspective. For this purpose, snow parameters such as snow onset day, snow cover duration (SCD), melt-out date and the snow cover area percentage (SCA) were employed to analyze spatio-temporal variability of snow cover over the course of 3 decades. On the regional scale, significant trends were found toward a shorter SCD at lower elevations in the south-east and south-west. However, our results do not show any significant trends in the monthly mean SCA [snow cover anomaly] over the last 27 yr. This is in agreement with other research findings and may indicate a deceleration of the decreasing snow trend in the Alpine region.

Given the importance of mountain regions for climate change assessment, this study recommends the complementary use of remote sensing data for long-term snow applications. It bears the potential to provide spatially and temporally comprehensive snow information for use in related research fields or to serve as a reference for climate models.